This invention relates to a disk type brake and more particularly to an improved brake of this type that is both hydraulically and mechanically operated and to an automatic adjustor for such brake.
Although the advantages of disk brakes for automotive applications have been acknowledged, the adoption of rear disk brakes has been slow. One reason for the reluctance of vehicle manufacturers to adopt rear disk brakes is the difficulty in providing an effective and compact parking brake. For the most part, the parking brake function has been provided by a separate pair of mechanically actuated brake pads. The use of a completely separate parking brake adds greatly to the expense.
It is, therefore, a principal object of this invention to provide an improved disk brake assembly that is both hydraulically and mechanically operated.
It is a further object of this invention to provide an improved dual actuated disk brake assembly in which both the hydraulic and mechanical actuators operate on the same brake pad.
Although disk brake structures have been proposed in which both hydraulic and mechanical actuators operate the same brake pad, the previously proposed devices have been relatively bulky. Specifically, such devices have had considerable dimension in the direction parallel to the axis of rotation of the brake rotor. As a result, it has been difficult if not impossible to fit such brakes into existing vehicles.
It is, therefore, a still further object of this invention to provide a compact hydraulically and mechanically operated disk brake assembly.
It is another object of this invention to provide a compact hydraulically and mechanically actuated disk brake assembly that may be conveniently fit into existing vehicles.
When both hydraulic and mechanical actuators operate on the same brake pad, it has been the practice to have the mechanical actuator operate on the piston of the hydraulic motor to achieve mechanical actuation. With such an arrangement, the intrusion of additional elements into the fluid motor presents problems in effecting good sealing of the fluid motor.
It is, therefore, yet another object of this invention to provide a hydraulically and mechanically actuated disk brake assembly with a minimum number of seals.
With hydraulically and mechanically operated disk brakes of the type described it has been the practice to position the mechanical actuator in a separate chamber in the brake housing assembly which chamber is adjacent the cylinder bore of the fluid motor. Previous constructions have provided seals around the externally operated component of the mechanical actuator to prevent fluid leakage. Such arrangements, however, present certain disadvantages in initial assembly line testing. If the seal of the externally operated mechanical element is good and the internal seal between the fluid motor and the mechanical actuator is bad, initial testing will fail to indicate this internal leakage.
It is, therefore, another object of this invention to provide a sealing arrangement for a combined hydraulically and mechanically operated disk brake assembly in which failures of the seals of the hydraulic portion of the brake may be readily detected.
Although many commercial forms of hydraulically operated disk brakes are inherently self-adjusting, mechanically operated disk brakes or combined hydraulically and mechanically operated disk brakes require some form of adjusting mechanism to permit compensation for lining wear. It has been the practice with brakes of the type described to provide an automatic adjustor between the mechanical actuator and the hydraulic piston for this purpose.
It is another object of this invention to provide an improved automatic adjustor for a disk brake assembly and to provide an improved mechanically and hydraulically operated disk brake embodying an improved automatic adjustor.